Ecological roles and release patterns of acylated homoserine lactones in Pseudomonas sp. HF-1 and their implications in bacterial bioaugmentation

Abstract

To enable development of a better bacterial bioaugmentation system for tobacco wastewater treatment, the roles and release patterns of acylated homoserine lactones (AHLs) in Pseudomonas sp. HF-1 were evaluated. Swarming was found to be induced by N-hexanoyl-homoserine lactone (C6-HSL) and N-3-oxo-hexanoyl-homoserine lactone (3-oxo-C6-HSL); the formation of extracellular polymeric substances (EPS) was induced by 3-oxo-C6-HSL, C6-HSL and N-3-oxo-octanoyl-homoserine lactone (3-oxo-C8-HSL); and biofilm formation was induced by C6-HSL and 3-oxo-C8-HSL. When the culture conditions were 25°C, pH 5–6, 3% inoculum, 1.5gL−1 nicotine and 1% NaCl, the amount of AHLs released was sufficient for quorum sensing of swarming and EPS formation for strain HF-1, which was beneficial to the startup stage during bioaugmentation. When strain HF-1 was cultured at pH 8 in the presence of 1.2–1.8gL−1 of nicotine and 1% NaCl, the threshold for quorum sensing of biofilm formation was reached and the bioaugmentation system showed an efficient performance.